I have immediate family members who are brother and sister. Both got engaged around the same time (to other people lol) and are getting married about 3 weeks from one another. The weddings are in the middle of summer. They live in the same city. Some other family members have been complaining that it's inappropriate for them to be doing this. It's obligating family from out of town to travel twice in a few weeks time period as well as wedding gifts. In my opinion it doesn't matter. I'm curious to see what others think!